Secrecy system



R. v. L. HARTLEY 1, 752 485 SECRECY SYSTEM April 1, 1930.

Filed Oct. 29, 1925 Patented Apr. 1-, 1930 UNITED STATES PATENT OFFICE.

RALPH V. I1, HARTLEY, OF SOUTH ORANQE, NEW JERSEY, ASSIGNOB TO WESTERN 'ELEUIRIO COMPANY, INCORPORATED, OF NEW YORK, N. Y.', .A GOBPORATTQN OF NEW YORK SECRECY SYSTEM Application filed October 29, 1925. Serial No. 65,505.

This invention relates to signaling systems andparticularly to arrangements for provld- 'ing secrecy in the transmission of messages over such systems.

An object of the invention is to transm t signals in such a manner that they shall be intelligible only at a properly equipped receiving station.

A feature of the invention is the provision of means in a signaling system employing a plurality of lines for simultaneously transmitting different messages thereover with secrecy, and in such a manner that each of the lines is, or may be, continuously utilized to full capacity for carrying messages.

In accordance with the invention, switching apparatus is provided at one station for dividing different telephone messa e waves into fragments on a time basis and or interchanging the fragment between difierent outgoing lines in such a manner as to make the transmitted messages unintelligible. At a receiving statipn corresponding switching apparatus operatin in synchronis'm with that at the transmitting station is provided to split-up the received waves into their component message fragments and to recombine the messa e fragments in their proper intelligiblc'or er. i

The invention will be clear from the following detailed description read'in connec-. tion with the accompanying drawing which illustratesa signaling system embodying the invention.

The signaling ing com rises a v ,eac of whic is arranged to be connected at one end in rotation to each one of a plurality of telephone stations S S S b means of a commutator or distributor D, an

system shown in the drawat the other end in rotation to each one of tributor D The stations 8,, S S 'and S S2, S are provided with the usual telephone transmitting and receivingequipment, which for simplicity is not shown in the drawing.

The distributors D and D maybe of an suitable type, the details of design depen ing upon the number of lines. over which mes urality of lines L L ,L,

- ring R with the segments of ring segments of ring R, with the segments of ring R The brushes on these radial arms are sages are to be transmitted. The type illustrated is designed for associating any one of three lines to any one of three stations. As

- the two-distributors, D and D, are identical and each of these ringscontains a plurality of segments also insulated from each other. The outer andinnerrings R and R have 9 segments each, which are'respe ctively desi nated a a and d --d while the intermed iate rings R and R have three segments each,

respectlvely, designated 6 b b and 0 0 0 The west and east terminals of the lines L L and L are respectively permanently connected to certain segments in the intermediate rings of distributors D and D, andthe terminals of the circuits leading from the statlons S S and S and stations S S and S, are respectively permanently connected to certain segments 1n the inner and outer rings of distributors D and D, as shown in the drawing.

A distributor brush holder H comprising I three rigidly connected radial'arms of nonconductmg material spaced 120 apart is mounted in the center of the distributor D and arranged to be rotated by a motor (not shown) whose shaft isconnected to the axis of two brushes, which, as the holder rotates, sweep over the distributor face and respectively connect in sequence the se ments of ft. and the respectively designated 13,--

.The distributor D- at the other end of theprime mark." n.

,the holder. Each of the radial arms carries Any suitable arrangement may be d fd E 1 synchronizingthe operation of the dfstrib tors D and D. The arran ement shown in the drawing is not a part of t e 1 .1 enti9n,

isidentical with the one illustrated and de-. scribed in the patent to Henry G. Egerton 'No. 1,400,039, dated December 13, 1921.

' ing frequencies carried by the line L The filter F in the repeater circuit RC connected across the line L is adapted to exclude the signaling frequencies and to pass the higher, frequencies from the sources 8 and 8 to a .vacuum tube repeater or combiner It, which produces in its output circuit, in addition to the frequencies from the sources 8 and 8 components representing the sum and difierence of these frequencies. The filter F in the output circuit of the repeater R is arranged to pass oscillations of the beat frequency comprising the difierence in the frequencies. of the sources 8 and 8 These beat oscillations are sent into the amplifier A and am 'lified 'suficiently to effect operation of the distributor magnet M, which governs the rate of travel of the brush holder H through the instrumentality of the escapement mechanism.

1 and ratchet 2, which may be frictionally connected to the shaft of the motor continuously driving the brush holder H.

At the east end of the line L the synchronizing apparatus comprising filters,repeater and amplifier, is a duplicate of the similarly designated apparatus alread described at the west end of the line. This a paratus is arranged to permit the beat OSClllations produced by the combination of cur= rents from the sources 8 and :2 received over the line L, to effect the operation of the distributor magnet M and cause it to step the b distributor D in synchronism with the distributor D at the west end of the line.

The operation of the system of the drawing as a secrecy system will now be explained in detail,

It will be assumed that three diflerent telephone messages are supplied to the distributor D from the circuits connected to stations S1 S and S respectively. In the position oi the brush holder H as shown in the drawing, station S isdirectl'yjconnected over line L with station S in a circuit which may be traced as follows: from one side of station S through conductor 3, segment a; of conductor ring R brush B segment 6 of ring R one side of line L segment b of ring R in dis tributor D, brush B segment o of ring R conductor 3, station S conductor 4, segment d ',-brush B segment 0 the other side of ling segment 0 of ring R of distributor 1);, brush B segment d, of ring R and conductor 4 back to station 8;. Tracin the circuits for the other statlons in a simllar manner it will be seen that for the position of I the brush holder H shown, station S is connected through line L with station S and station S is connected through line L with station S8. Now if the distributor brush holder'I-I is rotated to the right by the motor (not shown) to a position 40 from its pres .ent position as shown in the drawing, the synchronizing arrangement described above will cause a corresponding movement of the distributor brush holder H at the other end of the lines to a position 40 to the left of its present position. For these changed pos tions of the brush holders H and H, station S will be connected with station S through the following circuit: from one side of station S conductor 3, segment (1,, brush B segment b upper Wire of line L segment b brush B segment a conductor 3, station S conductor 4', segment d brush B segment a lower wire of line L segment 0 brush B segment (5 conductor 4, to the other side of station 8,. In a similar mannerthe circuits may be traced toshow'that for these changed positions of the brush arms, station S will be connected to station 8,, through line L and station S connected to station S through line L If the brush holder'H is rotated to the right another 40, or 80 from its position as shown in the drawing, causing the corresponding advancement to the left of brush holder H.

brush arm H 40 further to the right, or

120 from the positionshown' in the drawing, will bring the radial arm's carrying the rushes in a position such that stations S S and S will be again connected to S S and S respectively, over lines L L and L as was the case in the first arrangement described above. It is evident from the above that in-every 120 advancement of the brush holders, the corresponding stations at each end of the lines are connected'together for a short interval in rotation over each of the lines L19 L2 and. L3. v i i I.

From the above detailed description of the operation of one embodiment of the invention, it apparent that the switching apparatus at one end of the system insures that difierent messages from the sources S S and S or from the sources S S and S for the arrangement described, of course, can be trary manner.' The degree of unintelligibility will, of course, depend upon the size of the message fragments, which may be controlled by varying the length of the commutator segments or the speed at which the distributor brushesare rotated. A particular advantage of the invention lies in the fact that each,

. message wave transmitted over the lines L L or L ma be continuous, that is, each line may be emp oyed to full capacity at all times in carrying messages. The switching ap- V paratus at the receiving end of the line, op-

crating .in synchronism with the switching apparatus at the transmitting end of the line,

breaks up the unintelligible waves received over each of'the lines, L Lg and L into their component message fragments and distributes these fragments to the proper re- ,ceiving stations combinedin their original intelligible order. In sucha system,v as described, it is apparent that an unauthorized observer by tapmessages are transmitted may be widely separated thus making it a ping one or more of the lines-will hear only unintelli ible fragments of several conversations. 1? en though the observer taps all three of the lines, he will not'be able to make out the messages transmitted unless he is acquainted with the particular arbitrary -man ner in which the messages are combined-and has the proper apparatus for separating them, and has this apparatus suitably synchronized. It is, of course, apparent that in practice the different lines over we ich the jumbled up ractical impossibility for any unauthorized 0 server to tap all of the lines simultaneously.

It is to be understood that the particular arrangement illustrated and describedmay be variously modified without departing in. any way from the spirit of. the invention as defin in the accompanying claims. For example, the invention has been described in connection with its application to three lines, but it is apparent that it is also applicable to any number of lines. Although an arbitrary manner of arranging the message fragments has been illustrated and described, it is apparent that the apparatus may be arranged to give any desired arrangement of the fragments. For

example,distributors or commutators at each end of the systems in accordance with the invention may be used in tandem or combined in any other manner to give any desired irregular order for the message fragments.

Moreover, although the invention has been illustrated and described in connection with its use in telephone systems, it is to be understood that it is applicable to telegraph systems as well.

' Although the invention has been illustrated and described as applied to ordinary telephone lines, it is not limited t9 such use but the signaling stations S S S, and S S S may be connected to h gh fre- I 1. The method of securing, secrecy in the transmission of telephone messages over a signaling system employing a plurality of transmission paths, which method comprises dividing different telephone message waves into, fragments on an arbitrary predetermined time basis, interchangin ments of the different messages etween the different paths in suchja manner that a substantially continuous unintelligible wave comprising fragments of each of the original waves is transmitted over each of said paths, and at a receiving point separating and recombining the transmitted fragments to reproduce the original message waves.

2. The method of securing secrecy in the transmission of telephone messages over a signaling system comprising a plurality of lines which method comprises diverting succes'sively occurring portions of different telephone message waves in rotation and at a redetermined rate into each of said lines in such a manner that a continuous unin telligible wave comprising portions of each of saidtelephone message waves transmitted over each of said lines,and at a receiving point separating the different message portions in the received wave and recombining them to reproduce the original message waves.

3. In a secret signaling system, a plurality of telephone message current sources, a plurality of outgoing lines, commutating means for dividing the telephone currents from each of said sources into fragments on a predetermined time basis, and for cyclically interchanging the fragments from the different telephone currents between the outgoing lines so that the resultant message wave transmitted over each of said lines is substantially continuous and unintelligible and commutating means operating in synchronism with the first-mentioned commutating means for separating the message fragments received over said lines, and for recombining them in their proper intelligible order.

. 4. In a secrecy system, a plurality of telephone transmitting stations, a plurality of lines, switching means for cyclically connecting each of said stations in rotation to one endthe frag- ISQ riod of connection of each transmitting and receiving station to a given line being predetermined and of small duration.

5. In a two-way secret signaling system, a plurality of lines, a plurality of signaling stationseach comprising telephone transmitting and receiving apparatus at each end of said lines, switching means for connecting each of the signaling stations at one end of said lines in'rotation for a predetermined intervalof time to each of said lines in such a manner that during the interval of time when agiven one of said stations is connected to a given line, each of the other stations at said end of said lines is connected for the same interval to a different one of the other lines, a second switching means operating in nchronism-with the first mentioned switching a manner that during the interval when a given one of said signaling stations at said other end of said lines is coneach of the other signaling stations at said other end of said lines is connected for the same interval to a difi'erent one of the other lines.

6. In a secret signaling system aplurality of telephone transmitting stations, a plurality of receiving stations, a pluralit- H J V i v of transmission lines therebetwee'n, switc in means for simultaneously connecting one 0 said transmitting stations to one end of one of said lines and another of said transmitting stations to one end of another of said lines and maintaining said transmission sta tions so connected for a predetermined small interval of time, and at the end of that interval for disconnecting the first-mentioned transmitting station from the first-mentioned line and connecting it to the second-meme tioned line while simultaneously disconnect ing the second-mentioned station from said second-mentioned line and connecting it to "said first-mentioned line, and a second switchin means operating in synchronism with' t e first-mentioned switchin means for simultaneouslyconnecting one said receiving stations to said first-mentioned line and another of said receiving stations to the other end of saig sal predetermined small interval of time, and at'the end of said interval for disconnecting the first-mentioned receiving station from said first-mentioned line and connecting it to said second-mentioned line while simultaneously disconnecting the second-mentioned receiving station from said secondmentioned line and connecting it to said firstmentioned line.

7. In combination in a secret signaling s sa corresponding number of signal stations each comprising telephone transmitting and receivin apparatus, and means for interchangea 1y connecting said stations with said paths for a predetermined period of time so that at any instant each station is connected to a different transmission path andto only one path, the period of connection of any station to a given transmission path being short in comparison'with' the length of time re quired to transmit an intelligible portion of a message.

8. In combination in a secret signaling stem, a multiplicity of signal transmission paths, a corresponding number of pairs of signal stations, each pair. comprisin a tele-' phone transmittin stationat one on of said paths and a telep the other end of saidpaths, and means for paths in accordance with a prearranged scheme so that at a given instant each pair of signal stations is connected to a difierent one of said paths and to only one ath, the period of connection of any pair 0 stations to a given transmission ath being short in comparison with the period of time required to transmit thereover an intelligible portion of a telephone message.

9. In combination in a secret signaling system, a multiplicity of signal transmission paths, a. corresponding number of pairs of signal stations, each pair comprising a telephone transmitting station at one end of said paths and a telephone receiving station at the other end of said paths, and means for interchangeably connecting each pair of said signal stations in succession to each of .said paths in accordance with a prearranged scheme so that signaling currents from each telephone transmitting station are transmitted continuously over said paths and at a 'ven instant each pair of signal stations is and to only one path, the period of connection of any pair of stations to a given transmission path being short in comparison with the period of time required to transmit thereone receiving station at- .connectedto a difierentone of said paths over unintelligible portion of a telephone 76 tem, three or more signal transmission pat s,

and synchronously opera switches at said terminals for simultaneo y connecting to each respective line a transmitter at one terminal and acooperating receiver at the other terminal and for simultaneously interchanging the connections'in rapid succession to cause the vspeech currents utilized by .each transmitter and its cooperating receiver at the opposite terminal to traverse first one line durm the interval inwhich said transmitter an its coo crating receiver are connected thereto an then another line durin the interval in which said transmitter an receiver are connected thereto while the speech currents utilized by another transmita ter and receiver traverse'said other line dur-' ing the interval in which said other transmitter and its cooperating receiver are connected thereto and then said first line during the interval in which said other transmitter and -V. L. HARTLEY.

memes so on, in rapid recurring time inter- 

